Such linear blocking apparatuses and modular systems for the securement and release of persons, objects or the like are used in many safety-relevant technical fields. Based on the example of a person to be secured in a fairground ride (rollercoaster), the working method of such a modular system and of a linear blocking apparatus is set out below.
FIG. 7 shows schematically a person P, who is secured by means of a modular system 18. The modular system 18 has a seat S and a locking device 16, which is configured as a safety bar. Between the two components, the person P sits in a secured state. The safety bar is pivotable about a pivot center Z in the pivot directions M1, M2. In a roller coaster ride it is on the one hand necessary that, after the person P has boarded, the safety bar 16 can be pivoted only downward and the seated person P, during the ride, is secured by this on the seat S, and on the other hand, after the completion of the ride, the safety bar 16 is freely movable or pivotable, so that this is swung away upward automatically of its own accord, or by action of the person P, and the person P is able to leave the seat S again. In order to ensure this working method, the modular system 18 has a linear blocking apparatus 100, which is coupled to the safety bar 16. The linear blocking apparatus 100 can be actuated such that it on the one hand releases the safety bar in both directions of the linear motion L1, L2, and thus the safety bar 16 in both pivot directions M1, M2, and on the other hand the downwardly directed linear motion L2 is blocked, so that analogously the upwardly direction pivot motion M2 of the safety bar is blocked. Moreover, a spring 17, which likewise constitutes a part of the modular system 18, is coupled to the safety bar 16 and the seat S. The spring 17 has the function of supporting an upwardly directed motion of the safety bar 16, which motion releases the person. In a further illustrative embodiment (not represented), the locking device 16 is configured as a linearly movable component.
It is known to design a linear blocking apparatus 100 of this type as a hydraulic component (hydraulic blocking). The linear blocking apparatus herein possesses a linear device which is mounted in guided arrangement in a housing. On the outer end face, i.e. on the end face facing away from the housing, of the linear device is found a first coupling element, which can be directly or indirectly coupled to the safety bar. On the opposite end face of the linear device sits cylindrically within the housing a hydraulic piston, which constitutes a part of the hydraulic system. By the targeted displacement of hydraulic fluid into chambers which in the linear direction on both sides adjoin the lateral piston surfaces, it is thus possible to block or release the motion of the linear unit within individual motional directions. In FIG. 7, the linear blocking apparatus 100 is represented merely schematically, a detailed representation of the hydraulic system, i.e. its individual components, and also the interconnection of these, having been dispensed with.
In hydraulic systems, problems arise, however, in respect of seal-tightness, since within the system only very small system pressures are necessary, so that the built-in seals cannot properly exert their sealing effect. Moreover, in hydraulic systems, a steady diffusion of gas generally takes place, which gas passes through into the fluid chamber, for instance via a nitrogen tank which is present or from outside, so that the damping property of the hydraulic fluid is offset by the springy effect of the diffused-in gas bubbles. During operation, the person to be secured then forms the impression that the locking device or safety bar is not working properly. This phenomenon is also therefore referred to as “spongy behavior”.
These problems, caused by the use of hydraulic components lead, on the one hand, to a high maintenance requirement and, on the other hand, to an increased safety risk during operation, since, in the event of a breakdown or decreasing impact of the hydraulic system, the fixing effect of the linear blocking apparatus or of the locking device can no longer be ensured.